Safety device for preventing passage of flame



Aug. 31,1926 1,597,729

w. w. SCHETTLER SAFETY DEVICE FOR PREVENTING PASSAGE OF FLAME Filed April 4, 1925 Patented Aug. 31, 1926.

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WESLEY W. SCI'IETTLER, 0F SPRINGFIELD, OHIO, ASSIG-NOE TO THEFOOSGASENGINE. COM-PANY, OF SPRINGFIELD, OHIG, A CQRPORATION OF OHIO.

SAFETY DEVICE FOR PREVENTING- PASSAGE 0F FLAME.

Application. filed April 4, 1925. Serial No. 20,854.

This inventionv relates to devices for preventing the passage of flame to a source of combustible mixture it particularly relating to a device. for preventing the flame occasioned by backfire from the cylinders of an internal combustion engine from passing to the crank case of the engine in an arrangement wherein a connection is made hetweenthe crank case and the cylinders for the purpose of eliminating the vapor in the crank case.

An object of my invention is toprovide a safety device of the character referred to which will be simple in construction and eif'ectivein its operation.

The invention consists in providing a safety device constructed with a normally open check valve located in the connection between the source of combustible mixture and the point of delivery thereof which is closable by the pressure of the gases occasioned for instance by backfire, in connection with a passageway between the valve andthe point of delivery of a tortuous character caloulatedto retard theflame of backfire until the valve has been closed by the pressure of the gases; the arrangement being further of such a; nature that the passageway through which the flame must travel to pass the check valve is consider ably longer than the length of the passage between the source of pressure occasioned by backfire and the valve head; the valve head-forming-in fact, a part of the passageway.

In the accompanying drawings:

Fig. 1' is a vertical section of a device embodying the improvements.

Fig. 2 is a section on the line 2-2 of Fig. 1.

One of the instances of danger is in connect-ion' withinternal. combustion engines in which. a passageway is provided between the crank case and the intake manifold. In gas engines so equipped it sometimes happens that a backfire occurs which causes an explosion in the crank case, thereby wrecking the engine. To overcome the danger of thepassage offlame inthisand other struc= turesl have devised the fcllowingr meat.

1 represents a portion of the intakemanifold and 2 aportion of the crank case. 7 3 and 3 represent the two sections of a tubular connection betweenthe crank case, and the manifold joined together in any suitable way. Each of these sectionshas a flange 3" so that they may. be bolted, respectively, to

the manifold and crank case and the lower section 3 also preferably hasa removable plate at by, which. access may be obtained to the interior; thereof. Formed. integrally with the lower. section 3 is a guide 5 and its spider like supporting arms 6. Slidably mounted in the guide 5 is a valve stem 7 having on its upperend; a valve 8 cooperatingwith. an interior valve seat 9 near the upper endof the section3. Alsointegrally formed with the. section. 3 is a. horizontally perforated. wall 10.having a central threaded opening 11 in whichis screwed a spring supporting sten1;12; The lower end of this ste1n12 has also screwed thereon a perforated disk 14:.Wl1iCl1 is seated against: an interior shoulder 15 nearthe lower end of said. section 3. A; nut 16 on the lower. end ofthe: steni12 serves to hold it in different positions of adjustment. The valve stem 7 has a flanged collar 17 pinned thereto and also pinnedto the. upper end of the support 12 is a flanged collar. 18. Interposed; between and supported. bythese collars is a coil spring 19 whichtends normally to hold the valve 8 inopen position shown, the

aflange on the collar 17; ooacting. with the lower end of the guide 5 t0=1iOT111 astopfor the opening movement; of. thevalve.

Secured to a boss 20 on the upper face of the valveS is a tube 21. which extends through the section Swithin a short distance of the upper end thereof; Secured to an inturned flange 22 on. the upper end of the section 3 is a second tube 23 which proj ects through the outer tube 21. inspaced relation therewith to a point. within close proximity to the boss 20. r

In operation the valve 8 normally stands in the open position as indicated under the action of the spring 19 and the vapor in crank case passesupwardly between the casing section 3 and the tube 21,. thence downw-imilybetween-i he 21. and

and thence upwardly through the tube 23. If backfire occurs the air and vapor in the tube 23 are compressed exerting a pressure upon the head 20 of the valve 8 thereby closing the valve against tension of the spring. IVhen such back fire occurs there is a rise of pressure in the passage 1. This is transmitted as a pressure wave through the tube 23, giving up its velocity head against the head of the check'valve 20 and closing the check valve 8 on its seat 9 against the spring 19. To this velocity head impulse is added a reaction pressure also tending to close the valve as there can be no passage of gases through the annulus bounded by the walls 21 and 23 until a sufiicient reaction is set up against 20. These changes of flow, in addition to providing an acting and reacting force for the closure of the valve, considerably extend the time necessary for the burning combustible gases to pass through the passage between the walls 21 and 23 to reach the seat 9 and by makingthe tubes 21 and 23 of suitable length any discrepancy between the rate of flame propogation, the rate of gaseous flow and the rate of acceleration of the valve in closing can be compensated. c

While I have shown a spring pressed valve, I do not desireto be limited to such an arrangement of valve as any valve which is arranged to stand normally open but close under pressure may be used to accomplish the result; Neither do I desire to passageway between the valve and the intake manifold as any passageway which-will delay the flame of backfire to permit the pressure occasioned by the backfire to close the valve in advance of the flame is contemplated.

lVhile I have described the invention in connection with the cylinders and crank shaft of an internal combustion engine, yet the invention is applicable to other structures in which there is danger of ignition of the combustible mixture flowing from the source of supply.-

Having thus described my invention, I claim:

.1. In a fire check device for combustible fluid having a valved opening and a passageway leading from said opening to a point of discharge, of a normally open valve controlling said opening, said valve forming a part of said passageway at an intermediate point in'said passageway whereby back pressure of gasses in said. passageway acts upon said valve at a point removed from the opening controlled by the same.

2. In a fire check device forcombustible fluid, a normally open Valve closable under pressure andcontrolling an opening therein, and a tortuous passageway between said opening and the place of discharge for thefluid, said valve being arranged to be subjected to back pressure in said passageway at a point remote from said opening.

3. In a fire check device for combustible fluid, a normally open valve closable under pressure in said device, said device having a passageway between. said valve and the place of discharge for said fluid extending away from said valve then toward the valve and then again away from said valve, said valve being arranged to be subjected to back pressure in said passageway at a point remote from said opening.

'4. In a fire check device for combustible fluid, a normally open valveclosable under pressure in said device, and a pair of telescoping tubes in said device between said extending within the said first mentioned tube to form a passageway leading back towards said valve and thence through said second tube. be limited to the exact form of tortuous 6. In a fire check device for combustible fluid, a valve in said device, a spring for holding said valve normally open, an open ended tube connected with said valve on the discharge side thereof to'form a passageway between the walls of said device and said tube, and a second open ended tube carried by saiddevice and leadingfrom the point of discharge for said fluid towards said valve to form a return passageway between said tubes and thence through saidsecond tube. V

7. In a fire check deviceof the character described, a guide in said device, a valve having a stem slidably mounted in said guide, and an adjustable support carried by said device, a spring between saidsupportiand said valve stem normally tending to hold said valve open, an open ended tube a connected with said valve, and 'a second open ended tube supported by said device telescoping saidvalve tube, said tube forming a tortuous passageway between the valve and said place of discharge.

8. A fire check device for combustible fluid having a valved opening and a normally open valve for said opening, and means I intermediate said valved opening and the outlet for said fluid whereby back pressure of the fluid due to ignition thereof will act upon'the valve at a point in the passage remote from said opening for the purpose of closing the valve.

9. A fire check device for combustible fluid having a valved opening and a nor- 5 inally open valve for said opening, and a tortuous passageway between said opening and the outlet for said fluid arranged so that hack-pressure of the fluid due to ignition Will act upon the valve at a point in said tortuous passage remote from said 10 valve for the purpose of closing the valve. In testimony whereof, I have hereunto set my hand this 2nd day of April, 1925.

WESLEY WV. SCHETTLER. 

